Re: [gentoo-user] [OT overheat] How to cause shutdown on overheat

[Daniel da Veiga]

On 9/30/06, reader@×××××××.com <reader@×××××××.com> wrote:
> Group, I recently built a ventilated stucture around my 4 desktops to
> try to quiet things down and get rid of the heat.
>
> I made no provision for forced shutdown in case of overheat, which is
> quite likely to happen if, for example the main ventilation fan went
> down for some reason.
>
> Well, that happened due to stupidity on my part with getting used to
> the new setup.  I fired up a computer and neglected to turn the fan
> on.  Then left it running overnight.
>
> Well, given the confined space and very little/no ventilation (of my
> homemade structure) the computer got hot...
>
> Sometime this morning I see syslog messages written to tty that say:
>
>   Message from syslogd@reader at Sat Sep 30 04:41:32 2006 ...
>   reader kernel: CPU0: Temperature above threshold
>
>   Message from syslogd@reader at Sat Sep 30 04:41:32 2006 ...
>   reader kernel: CPU0: Running in modulated clock mode
>
> [...]
>
> Some kind of attempt by kernel to cool things down.  But will it
> actually shutdown if it gets dangerously hot?
>
> Further, how can I discover what temperatures were involved when this
> happened?
>
> Or can I set something to make a shutdown happen at a specific
> temperature?
>
> A nicer solution would be somekind of added stand alone temperature
> monitor in the enclosure that causes a controlled shutdown like one
> gets with `shutdown -h now'.
>
> Anyone here with some experience in this kind of thing that can steer me
> to some good information?
>

If you have built your kernel with ACPI options for THERMAL or some
kind of frequency changer, you can use a daemon like cpufreqd to
monitor the temperature and take actions like reduce the clock and
voltage to avoid damage to the processor.

http://www.gentoo.org/doc/en/power-management-guide.xml

When my computer reaches the limit (wich in my case is 73 degrees C)
it automatically shutdown, I didn't have to configure anything, it is
builtin with the thermal ACPI module. I'm talking about a Pentium IV
Northwood here, and they tend to get really hot. It used to happen to
my Athlon XP also... To monitor the temperature, you can read the
/proc entries created by ACPI, for example
/proc/acpi/thermal/TZ0/info.

-- 
Daniel da Veiga
Computer Operator - RS - Brazil
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